CIA director John Brennan acknowledged Thursday that U.S.-led efforts against ISIS have not reduced its "terrorism capability and global reach," saying it remained a "formidable adversary."

"Unfortunately, despite all our progress against ISIL on the battlefield and in the financial realm, our efforts have not reduced the group's terrorism capability and global reach," he said before the Senate Intelligence Committee. "The resources needed for terrorism are very modest, and the group would have to suffer even heavier losses on territory, manpower and money for its terrorism capacity to decline significantly.

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"Moreover, the group's foreign branches and global networks could help preserve its capacity for terrorism regardless of events in Iraq and Syria. As the pressure mounts on ISIL, we judge that it will intensify its global terror campaign to maintain its dominance of the global terrorism agenda."

The CIA director's statement comes on the heels of the worst terror attack since Sept. 11 on Sunday, when a Muslim man who pledged allegiance to ISIS killed 49 people at a gay Orlando night club.

Brennan said ISIS, or ISIL as Obama administration members refer to it, had lost territory in Iraq and Syria and was struggling to replenish fighters.

"ISIL, however, is a formidable, resilient and largely cohesive enemy, and we anticipate that the group will adjust its strategy and tactics in an effort to regain momentum," he said.

He also said the anti-ISIS coalition's efforts had reduced its ability to gain revenue, but ISIS still was managing to generate "tens of millions of dollars" per month thanks to taxation and oil sales.

Referencing the attacks in Orlando and San Bernardino, Brennan laid out the threat of ISIS attempting to inspire more attacks from people with no "direct link" to the group.

"In sum, ISIL remains a formidable adversary, but the United States and our global partners have succeeded in putting the group on the defensive, forcing it to devote more time and energy to try to hold territory and to protect its vital infrastructure inside of Syria and Iraq," he said. "And though this will be a long and difficult fight, there is broad agreement in the international community on the seriousness of the threat and on the need to meet it collectively and decisively."

David Rutz is managing editor of the Washington Free Beacon. He was previously a sports reporter for two years in Atlanta and has done freelance sports reporting for the Washington Post. He graduated from Vanderbilt University in 2010 and lives in Marietta, Ga. His Twitter handle is @DavidRutz.